3 ms·

Doesn’t look like the actual airframe is degrading, it’s the nose it’s likely the composite RADOME that is degrading, if it’s even material degradation the dama

Doesn’t look like the actual airframe is degrading, it’s the nose it’s likely the composite RADOME that is degrading, if it’s even material degradation the damage looks almost like a bird or an object strike. The description of the internal structure also seems to be quite similar to other RADOME even marine ones.

jjoonathan 7y ago
Over the last decade or so I've gotten the chance to use a number of antenna /accessories made of uwave RADOME plastic from a few different vendors and in all cases the plastic was cracked, crumbling, taped together, etc. It seems like a systematic problem. I bet there are a bunch of polymer chemists who know exactly what's going on.
- dogma1138 7y ago
  I have a feeling that it's a combination of two things. 1) The plastics might need to be made out of a very specific material which might not be very stable in the long term. 2) RADARs get freaking bloody hot and even a few % of absorption might be enough to essentially make them into a microwave oven. I'm guessing some combination of the material, pure heat and radiation might be the cause of these plastics breaking down but I'm not a material engineer however this is something that I've also encountered. I have had experience with SAR pods and their RADOMEs have had to be constantly replaced due to degradation as well. In fact in spot/strip mode it wouldn't be uncommon to see actual discoloration of the RADOME after a few flights.
  - jjoonathan 7y ago
    Most of the crumbling RADOME material I've seen has been on receive-only antennae, because that's what I deal with regularly, so I don't think it's purely a power thing. My working hypothesis is more in line with your (1), that plasticizer is the major absorbing component of the plastic, so to make RADOME plastic you just leave out the plasticizer and live with crumbly plastic. But I'm no polymer chemist, so that's really just speculation.
starpilot 7y ago
Doesn't look like the radome. The radar antenna is inside the nosecone: http://www.f22fighter.com/f22cutaway.jpg http://www.f22fighter.com/f22cutaway.jpg whereas the cracking appears to be on the skin covering avionics.
- dogma1138 7y ago
  We don't know how far back the RADOME goes on aircraft with nose installed MLDS with radar lock detection the the RADOME might extend to the cockpit. Pod based MLDS systems are essentially made from the same materials as RADOMEs for this reason.

jjoonathan 7y ago

Over the last decade or so I've gotten the chance to use a number of antenna /accessories made of uwave RADOME plastic from a few different vendors and in all cases the plastic was cracked, crumbling, taped together, etc. It seems like a systematic problem. I bet there are a bunch of polymer chemists who know exactly what's going on.

dogma1138 7y ago
I have a feeling that it's a combination of two things. 1) The plastics might need to be made out of a very specific material which might not be very stable in the long term. 2) RADARs get freaking bloody hot and even a few % of absorption might be enough to essentially make them into a microwave oven. I'm guessing some combination of the material, pure heat and radiation might be the cause of these plastics breaking down but I'm not a material engineer however this is something that I've also encountered. I have had experience with SAR pods and their RADOMEs have had to be constantly replaced due to degradation as well. In fact in spot/strip mode it wouldn't be uncommon to see actual discoloration of the RADOME after a few flights.
- jjoonathan 7y ago
  Most of the crumbling RADOME material I've seen has been on receive-only antennae, because that's what I deal with regularly, so I don't think it's purely a power thing. My working hypothesis is more in line with your (1), that plasticizer is the major absorbing component of the plastic, so to make RADOME plastic you just leave out the plasticizer and live with crumbly plastic. But I'm no polymer chemist, so that's really just speculation.

starpilot 7y ago

Doesn't look like the radome. The radar antenna is inside the nosecone: http://www.f22fighter.com/f22cutaway.jpg http://www.f22fighter.com/f22cutaway.jpg whereas the cracking appears to be on the skin covering avionics.

dogma1138 7y ago
We don't know how far back the RADOME goes on aircraft with nose installed MLDS with radar lock detection the the RADOME might extend to the cockpit. Pod based MLDS systems are essentially made from the same materials as RADOMEs for this reason.